Open notepad and copy/paste this:
Dim Message, Speak
Message=InputBox("Enter text","Speak")
Set Speak=CreateObject("sapi.spvoice")
Speak.Speak Message
Then save it as a .vbs instead of the txt.
When you open it a window will come up with a text field. Whatever you type in the text field is spoken by your computer.
(Be sure your volumn is on)